The present invention concerns acoustical structures, and more particularly, relates to an acoustical panel system for constructing walls, fences and the like with enhanced noise reduction properties.
Acoustical structures can be employed to reduce either the transmission of sound or the reflection of sound, or both. The ability of an acoustical structure to reduce the transmission of sound can be measured by what is known as the insertion or transmissive loss of the structure. Similarly, the ability of an acoustical structure to reduce the reflection of sound can be measured by the absorption or reflective loss of the structure. In general, the higher the loss factor, the more effective is the acoustical structure in reducing the transmission or reflection of sound, as the case may be.
The need for acoustical structures can arise in both exterior and interior applications. For example, in urban settings it may be desired to shield residential neighborhoods from traffic noise generated by nearby freeways, expressways, railway tracks and the like. The conventional solution is to build a large wall made of bricks or cement cinder blocks alongside the thoroughfare. Although relatively expensive and labor intensive to construct, these walls are generally adequate as barriers to sound transmission. However, this solution to the noise problem suffers from the fact the walls also tend to be highly reflective, that is, they have a low absorption loss factor, with the result that they cause the level of traffic noise to increase on the thoroughfare side of the barrier. Moreover, to be effective noise barriers the walls may need to be so high as to create an unwanted visual obstruction and interfere with the receipt of natural light on one or both sides of the wall.
Applications for acoustical structures also arise in connection with buildings, whether the need is to control the acoustics of the building vis-a-vis its exterior or from room to room within the interior of the building. Here, a conventional solution is to use relatively thick panels to cover underlying structural support members. Again, such panels can be an effective barrier to sound transmission, but they too tend to be highly reflective. In addition, these panels have a similar problem of possibly creating an unwanted visual obstruction and interfering with the receipt of natural light from the outside, unless interrupted with windows, which only tends to exacerbate the problem of acoustic reflection. Moreover, when used on the exterior of a building, these cover panels require significant rigidity and strength to resist wind loading forces and the like that could otherwise deform, dismember or dislodge them. Consequently, these cover panels likewise tend to be heavy, labor intensive to install, and relatively expensive.
Accordingly, there exists a need for an effective noise barrier system that reduces both transmitted and reflected sound, transmits light, is lightweight, economical and easy to construct, and has the structural integrity to resist wind loading forces and the like. The present invention fulfills these needs.